having many probs on my 125

Hello. I have an 03 yz 125. First off I never could jet it right. I think i needs a leaner pilot but im not sure. For example when im racing and i come down off of a big jump and I nail the throttle there is a hesitation. And then when i land the bike takes a while to rev. I know that I am high enough in the powerband to keep it from bogging. Is this due to to rich of a pilot? The bike has a V Force in it but when i put that in i didnt fell hardly if any power gain or snap. My secong problem with the bike is the fact that it almost seems like it has a lazy gear. 3'rd gear just doesnt rev as tho 4th and 5th or even 2nd and first do. This has pondered me for some time now. Both mxa and dirt rider siad that the tranny has noticible jumps sometimes but this is a constant feeling. Is this a lemon bike or what? I also saw the internals of a 99 yz 125 come up for sale on ebay. I am interseted would it be a bad idea to drop those into my bike to turn it back into a 6 speed? The cases are the same and to my knowledge it would be a fine transaction. What are you solutions to my problems? Thanks,.

I have added 2 teath on my rear sprocket already. I dont think it is the flowt bowl however because it will do it sometimes going into a corner or shifting. And the heighth seems normal it spills gas out at the slightest lean over. I am really in question about the tranny tho. Thanks